The present invention relates to embedding a thermally sensitive material into an organic substrate supporting semiconductor circuits, and more specifically, to a thermally sensitive material that permanently changes color when the substrate is subjected to a particular temperature during a manufacturing process.
Organic substrates used for semiconductor module manufacturing are sensitive to exposure to excessive temperature. When exposed to excessively high temperature, the result may have negative effects on the product quality, performance and reliability when processed through assembly. All parts are qualified to a maximum temperature they can be exposed to and still function properly.
The materials currently used for organic packaging are sensitive to the maximum temperature associated with processing. Minimum temperatures are required to make a good assembly solder joint, however, misprocessing by overheating may result in semiconductor module failure. Industry specifications have been written by JEDEC Solid State Technology Association to specify the maximum exposure to certain temperature conditions.
All of the internal qualifications are performed to determine the maximum exposure temperature and the number of times parts can be exposed to those temperatures. Excessive exposure to high temperature can result in immediate or time dependent failure. Most process steps are designed to ensure compliance.
The most heat intensive operation occurs when failed semiconductor modules are removed from modular assemblies for off-line failure analysis. However, excessive temperature at this modular removal step may cause failure modes of the failed semiconductor modules which have nothing to do with the original failure.
Because it is not always possible to know exactly the temperature which parts are exposed to, it is difficult to ascertain the true failure mechanism and root cause. Therefore, temperature exposure must be controlled and more thoroughly monitored at all processing steps. There is no current method to record and visually show the level of temperature to which a part has been exposed.